What header is used to define the cache policy determined by the server?

The Cache-Control header is essential for defining the caching policies determined by the server. It allows the server to instruct the client (and intermediate caches) on how to handle the storage of the response. This includes directives such as how long the resource should be cached, whether it is cacheable or not, and conditions under which the cache should be revalidated. By using Cache-Control, developers can optimize resource delivery, ultimately improving performance and the end-user experience.

Other headers mentioned serve different purposes. For instance, the Content-Type header specifies the media type of the resource, while the Authorization header is used for user authentication. The WWW-Authenticate header is necessary for defining how a client can authenticate itself to the server, particularly in relation to accessing protected resources. Therefore, while each header plays a distinct role in the HTTP protocol, Cache-Control specifically addresses caching behavior, making it the correct choice in this context.